Treadmill frame



FIG. 1 is a perspective view of a treadmill frame showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof; and,

FIG. 6 is a top plan view thereof.

The broken lines depict parts of treadmill frame that form no part of the claimed design. 

CLAIM The ornamental design for a treadmill frame, as shown and described. 